Далайн түвшин нэмэгдсэний улмаас усанд автсан эртний ойн хөрс нь өдгөө далайн амьтдын амьдрах орчин болсон “хүлэр хад” болон хувирсан нь тогтоогдсон байна.
Мозамбикийн Базаруто олтригийн орчимд хийсэн судалгаагаар эртний ой, намагт газрын үлдэгдэл нь далайн экосистемийн чухал хэсэг болж байгааг тогтоожээ. Scientific Reports сэтгүүлд нийтлэгдсэн судалгаагаар, эдгээр “хүлэр хад” нь ойролцоогоор 300-5000 жилийн өмнө бүрэлдсэн болохыг нүүрстөрөгчийн он цаг тогтоох аргаар баталсан байна. Далайн түвшин нэмэгдэж, эрэг орчмын газар нутаг усанд автах үед ургамлын үлдэгдэл элс, далайн усанд дарагдаж, улмаар долгионы нөлөөгөөр элс нь хуулагдан хүлэр давхарга ил гарчээ.
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Эдгээр хүлэр хаданд хадгалагдаж буй нүүрстөрөгчийн хэмжээ болон тэдгээрийн хүрээлэн буй орчинд үзүүлэх нөлөөг одоогоор бүрэн судлаагүй байна. Судлаачид хүлэр давхаргын зузаан, нягтрал, элэгдлийн түвшин болон хүлэмжийн хийн солилцоог нарийвчлан тодорхойлох шаардлагатай байгааг тэмдэглэжээ. Ижил төстэй байгалийн тогтоц Зүүн өмнөд Ази, Карибын тэнгис болон Баруун Африкийн эрэг орчмуудад байх магадлалтай гэж эрдэмтэд таамаглаж байна.
Дэлгэрэнгүйг эх сурвалжаас харах
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Thousands of years after disappearing beneath the ocean, ancient forests off Mozambique’s coast are full of life again. Their remains have turned into underwater reefs packed with fish and other marine animals, supporting a level of biodiversity that rivals nearby coral reefs, even though there’s no living coral in sight.
The discovery comes from the Bazaruto Archipelago, where researchers found that the remains of ancient coastal forests and swamps have become an unexpected home for marine life. These formations, known as peat reefs, developed as rising seas swallowed the land and waves gradually uncovered the old forest floor.
The findings, published in Scientific Reports, offer the first detailed look at the biodiversity of tropical peat reefs. They also bring up another intriguing question: how much carbon from those long-lost forests is still sitting beneath the waves?
A Forest That Becomes an Underwater Reef
It started with forests and swamps growing along what was once Mozambique’s coastline. As trees and plants died, their remains built up in wet ground, slowly forming peat, a dense material rich in organic carbon. Then the sea moved in. Rising water levels flooded the coastal landscape, burying the vegetation beneath sand and seawater. Over time, waves swept away parts of that sand, revealing solid layers of peat on the ocean floor.
According to the study in Scientific Reports, radiocarbon dating shows that these deposits formed between roughly 300 and 5,000 years ago. Some samples contain as much as 40% organic carbon by dry weight. Today, the reefs sit just 2 to 4 meters below the surface, where conditions aren’t exactly gentle. Water temperatures can swing between 24.5°C and 28.6°C in a single day, while tides, storms, and cyclones constantly reshape the seabed.
Some reefs get buried under shifting sand and others are uncovered or broken apart by waves. Yet marine life continues to occupy these ancient surfaces.
A Reef Without Coral, but Full of Life
Researchers examined three peat reefs and compared them with a nearby coral reef. They counted 26 to 36 small fish species on each peat reef, finding a level of fish diversity comparable to the coral habitat. But look closer, and the differences become clear.
Instead of colorful coral colonies, these reefs are covered with seagrasses, seaweeds, oysters, and barnacles. Cracks in the peat provide hiding places for spiny lobsters and young fish, including snappers and grunts. Sharks, rays, and turtles were also recorded across the two reef types.
“What was once a forest floor is now a nursery for reef fish,” said Dr. Mario Lebrato, lead author of the study and co-founder of the Bazaruto Center for Scientific Studies.
Part of the explanation lies in the surrounding landscape. Much of this stretch of Mozambique’s seabed consists of shifting sand, with few naturally solid surfaces. The exposed peat gives marine animals somewhere to settle, find food, and escape predators. Interestingly, while the peat and coral reefs share many fish species, the invertebrates attached to their surfaces are very different.
Underwater Forests May Still Store Ancient Carbon
There’s another side to this discovery, and it has little to do with fish. The old forest remains contain carbon that has stayed trapped in the peat for thousands of years. Just how much is still there, though, nobody knows.
According to the Bazaruto Center for Scientific Studies, coastal peat swamps on land can hold 1,000 to 2,000 tons of carbon per hectare below ground. Researchers haven’t yet worked out how much the submerged reefs contain, or whether they’re currently absorbing or releasing carbon. To find out, scientists need to measure the thickness and density of the peat, track erosion, and study how carbon and greenhouse gases move through these habitats.
And Mozambique might not be the only place hiding them. The researchers suggest that similar peat reefs could exist along coastlines in Southeast Asia, the Caribbean, and West Africa, where old coastal landscapes may also have disappeared beneath rising seas.
The discovery was made possible by the BCSS Ocean Observatory, which has gathered more than 22 million measurements across roughly 6,850 square kilometers since its establishment in 2017. The researchers want that to change, particularly because these formations provide shelter for marine species and preserve carbon from long-gone coastal ecosystems.
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